Things that belong in cookies:
chocolate in any form
raisins or craisins
science things that make them cookie-like (baking soda, baking powder, etc)
Things that do not belong in cookies:
If you are having trouble remembering the Dos and Don'ts of cookie baking, it may be helpful to think of it this way: "Don't be a rookie - no veggies in a cookie." Or (now this one isn't going to rhyme, so don't get your hopes up), "If I can put it in my soup, I shouldn't put it in my cookie dough." I mean, would you make chicken cookies? Minestrone cookies? Of course not. So stop, I beg you, just don't do it.
Another helpful way to remember is to think of when you can eat these things. For example, vegetables and legumes belong in the meal, like in an appetizer, entree or side dish. Cookies, on the other hand, belong in your hand at any time of day or night. Mmmmmm.
There have been lots of recipes going around on Facebook promising delicious cookies using very non-delicious ingredients. Do not be duped. I promise you that that cookies made with mashed chickpeas will taste like ... well, exactly as a cookie made out of chickpeas should taste. What were you expecting, fool???
You know, I'm not anti-vegetable at all. It's just that it's so tiring having to worry all the time about "being healthy" and "things that are good for you" and "how can I sneak some lentils and broccoli into this dessert?" Can't we, once in a while, make delicious food (cookies come to mind, for example) and eat it just because it tastes good???
RT if you believe in the Pure Cookie Movement.